The TrackPoint class of pointing devices employ a ceramic strain gauge balanced resistive bridge network as an isometric sensor for user input. A manipulation lever is attached to a central point on the strain gauge. Force applied to the lever causes the four resistive elements to change resistance in proportion to the amount each is distorted by the applied force. The resistances are measured and a mathematical transformation is performed to convert the changes in resistance to standard mouse-type output signals. In a specific embodiment, the output signals conform to the IBM P/S-2 computer pointing device standard. Basically, the standard mouse-type signals represent velocity in a two-dimensional space. The velocity in a given direction is proportional to the applied force in that direction. Such a pointing device is used, for example, to manipulate a graphical user interface on a computer display screen.
A prior art figure ("PRIOR ART") illustrates the manner in which specific embodiments of the TrackPoint pointing devices are used. The manipulation lever 1 extends from a strain gauge 2, through an opening between several keys 3 of a computer keyboard 4. The circuits 5 which are connected to the strain gauge are located at some distance from the strain gauge and include analog-to-digital converters, digital formatting and power regulation. The low-level analog signals from the strain gauge are connected to the circuits via a cable 6. Though the combination works well, the cable must be assembled and connected by hand, thus increasing the manufacturing cost of the whole assembly.
It would be desirable to eliminate the cost of the manufacturing and assembly steps involving the inter connecting cable.